Gestation of a Pony, No contact with stallion in 369 days. Is large and has milk. How much longer??

I keep reading about 345ish days and I am watching my mare as close as I can. I bought her and had no clue she could be bred. She just keep getting bigger and her udder is getting fuller and she has milk. I have also been told it is out of season.... It is really cold here, I am fearfull for the foal in the cold